US8562194B2ActiveUtilityPatentIndex 41
Wavelength conversion unit and illumination apparatus including the unit
Est. expiryJan 20, 2030(~3.5 yrs left)· nominal 20-yr term from priority
G02B 6/0003G02B 6/262G02B 6/0008
41
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Cited by
2
References
4
Claims
Abstract
A wavelength conversion unit includes a wavelength conversion member that transmits a part of incident excitation light and converts a part of the excitation light into wavelength-converted light having a wavelength different from a wavelength of the excitation light to emit the wavelength-converted light. The excitation light has an intensity distribution in which an intensity is maximum at the center and decreases as getting apart from the center. A thickness of the wavelength conversion member at a portion into which light at the center of the intensity distribution of the excitation light enters is larger than those at any other portions.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. A wavelength conversion unit comprising a wavelength conversion member that transmits a part of incident excitation light and converts a part of the excitation light into wavelength-converted light having a wavelength different from a wavelength of the excitation light to emit the wavelength-converted light,
wherein the excitation light has an intensity distribution in which an intensity is maximum at a center and decreases as getting apart from the center, and
a thickness of the wavelength conversion member at a portion into which light at the center of the intensity distribution of the excitation light enters is larger than those at any other portions,
wherein the wavelength conversion member has a rotationally symmetric shape, the excitation light enters the wavelength conversion member so that light at the center of the intensity distribution travels along a central axis of the wavelength conversion member, and the wavelength conversion member has a thickness such that an intensity of the excitation light having passed along the central axis of the wavelength conversion member is generally equal to an intensity of the excitation light having passed through the wavelength conversion member via a point on at least one circular circumference having the center at the central axis inside a region irradiated with the excitation light,
wherein the excitation light that enters the wavelength conversion member has an intensity distribution approximated to a Gaussian distribution, and the thickness of the wavelength conversion member coincides with a transmission intensity uniforming thickness function on the central axis and the circular circumference, where the transmission intensity uniforming thickness function is a function of the thickness of the wavelength conversion member with which an intensity distribution of the excitation light having passed through the wavelength conversion member becomes constant in the range of a predetermined distance from the central axis of the wavelength conversion member, and
wherein the transmission intensity uniforming thickness function is represented by the following expression:
d
(
x
)
=
d
0
-
kx
2
…
x
≤
(
d
0
/
k
)
1
/
2
=
0
…
x
>
(
d
0
/
k
)
1
/
2
k
=
2
log
10
e
α
·
w
2
where x is a distance from the central axis, d(x) is a thickness of the wavelength conversion member at the distance x, d 0 is a thickness of the wavelength conversion member on the central axis, α is an absorption coefficient that is a ratio that the excitation light is absorbed by the wavelength conversion member per unit thickness, and w is a radius of the irradiated region.
2. A wavelength conversion unit comprising a wavelength conversion member that transmits a part of incident excitation light and converts a part of the excitation light into wavelength-converted light having a wavelength different from a wavelength of the excitation light to emit the wavelength-converted light,
wherein the excitation light has an intensity distribution in which an intensity is maximum at a center and decreases as getting apart from the center, and
a thickness of the wavelength conversion member at a portion into which light at the center of the intensity distribution of the excitation light enters is larger than those at any other portions,
wherein the wavelength conversion member has a rotationally symmetric shape, the excitation light enters the wavelength conversion member so that light at the center of the intensity distribution travels along a central axis of the wavelength conversion member, and the wavelength conversion member has a thickness such that an intensity of the excitation light having passed along the central axis of the wavelength conversion member is generally equal to an intensity of the excitation light having passed through the wavelength conversion member via a point on at least one circular circumference having the center at the central axis inside a region irradiated with the excitation light,
wherein the excitation light that enters the wavelength conversion member has an intensity distribution approximated to a Gaussian distribution, and the thickness of the wavelength conversion member coincides with a transmission intensity uniforming thickness function on the central axis and the circular circumference, where the transmission intensity uniforming thickness function is a function of the thickness of the wavelength conversion member with which an intensity distribution of the excitation light having passed through the wavelength conversion member becomes constant in the range of a predetermined distance from the central axis of the wavelength conversion member,
wherein the thickness of the wavelength conversion member coincides with the transmission intensity uniforming thickness function at a position where an incident intensity of the excitation light into the wavelength conversion member is 1/e n (n is a natural number) of an incident intensity on the central axis,
wherein the thickness of the wavelength conversion member coincides with the transmission intensity uniforming thickness function inside the irradiated region, and
wherein, assuming that α is an absorption coefficient that is a ratio that the excitation light is absorbed by the wavelength conversion member per unit thickness, the thickness of the wavelength conversion member is smaller than the thickness of the same on the central axis by (1/α)log 10 e at a position where an incident intensity of the excitation light is 1/e of an incident intensity of the same on the central axis, and the thickness of the wavelength conversion member is smaller than the thickness of the same on the central axis by (2/α)log 10 e at a position where an incident intensity of the excitation light is 1/e 2 of the incident intensity of the same on the central axis.
3. An illumination apparatus comprising:
an excitation light source that emits excitation light; and
a wavelength conversion unit having a wavelength conversion member that receives the excitation light, transmits a part of the excitation light, and converts a part of the excitation light into wavelength-converted light having a wavelength different from a wavelength of the excitation light to emit the wavelength-converted light,
wherein the excitation light has an intensity distribution in which an intensity is maximum at a center and decreases as getting apart from the center, and
a thickness of the wavelength conversion member at a portion into which light at the center of the intensity distribution of the excitation light enters is larger than those at any other portions;
the illumination apparatus further comprising:
a light guide member that guides the excitation light from the excitation light source to the wavelength conversion unit, wherein the wavelength conversion member has a rotationally symmetric shape, an exit end portion of the light guide member is arranged coaxially with the wavelength conversion member, the excitation light enters the wavelength conversion member so that light at the center of its intensity distribution travels along a central axis of the wavelength conversion member, and the wavelength conversion member has a thickness with which an intensity of the excitation light having passed through the wavelength conversion member on the central axis becomes generally equal to an intensity of the excitation light having passed through the wavelength conversion member via a point on at least one circular circumference having the center at the central axis inside a region irradiated with the excitation light,
wherein the excitation light that enters the wavelength conversion member has an intensity distribution approximated to a Gaussian distribution, the thickness of the wavelength conversion member coincides with a transmission intensity uniforming thickness function on the central axis and the circular circumference, where the transmission intensity uniforming thickness function is a function of the thickness of the wavelength conversion member with which an intensity distribution of the excitation light having passed through the wavelength conversion member becomes constant in the range of a predetermined distance from the central axis of the wavelength conversion member,
wherein the transmission intensity uniforming thickness function is represented by the following expression:
d
(
x
)
=
d
0
-
kx
2
…
x
≤
(
d
0
/
k
)
1
/
2
=
0
…
x
>
(
d
0
/
k
)
1
/
2
k
=
2
log
10
e
α
·
w
2
where x is a distance from the central axis, d(x) is a thickness of the wavelength conversion member at the distance x, d 0 is a thickness of the wavelength conversion member on the central axis, α is an absorption coefficient that is a ratio that the excitation light is absorbed by the wavelength conversion member per unit thickness, and w is a radius of the irradiated region.
4. An illumination apparatus comprising:
an excitation light source that emits excitation light; and
a wavelength conversion unit having a wavelength conversion member that receives the excitation light, transmits a part of the excitation light, and converts a part of the excitation light into wavelength-converted light having a wavelength different from a wavelength of the excitation light to emit the wavelength-converted light,
wherein the excitation light has an intensity distribution in which an intensity is maximum at a center and decreases as getting apart from the center, and
a thickness of the wavelength conversion member at a portion into which light at the center of the intensity distribution of the excitation light enters is larger than those at any other portions,
the illumination apparatus, further comprising:
a light guide member that guides the excitation light from the excitation light source to the wavelength conversion unit, wherein the wavelength conversion member has a rotationally symmetric shape, an exit end portion of the light guide member is arranged coaxially with the wavelength conversion member, the excitation light enters the wavelength conversion member so that light at the center of its intensity distribution travels along a central axis of the wavelength conversion member, and the wavelength conversion member has a thickness with which an intensity of the excitation light having passed through the wavelength conversion member on the central axis becomes generally equal to an intensity of the excitation light having passed through the wavelength conversion member via a point on at least one circular circumference having the center at the central axis inside a region irradiated with the excitation light,
wherein the excitation light that enters the wavelength conversion member has an intensity distribution approximated to a Gaussian distribution, the thickness of the wavelength conversion member coincides with a transmission intensity uniforming thickness function on the central axis and the circular circumference, where the transmission intensity uniforming thickness function is a function of the thickness of the wavelength conversion member with which an intensity distribution of the excitation light having passed through the wavelength conversion member becomes constant in the range of a predetermined distance from the central axis of the wavelength conversion member,
wherein the thickness of the wavelength conversion member coincides with the transmission intensity uniforming thickness function at a position where an incident intensity of the excitation light into the wavelength conversion member is 1/e n (n is a natural number) of an incident intensity on the central axis,
wherein the thickness of the wavelength conversion member coincides with the transmission intensity uniforming thickness function inside the irradiated region,
wherein, assuming that cc is an absorption coefficient that is a ratio that the excitation light is absorbed by the wavelength conversion member per unit thickness, the thickness of the wavelength conversion member is smaller than the thickness of the same on the central axis by (1/α)log 10 e at a position where an incident intensity of the excitation light is 1/e of an incident intensity of the same on the central axis, and the thickness of the wavelength conversion member is smaller than the thickness of the same on the central axis by (2/α)log 10 e at a position where an incident intensity of the excitation light is 1/e 2 of the incident intensity of the same on the central axis.Cited by (0)
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